X-Git-Url: https://plomlompom.com/repos/berlin_corona.txt?a=blobdiff_plain;ds=sidebyside;f=plomtask%2Fdb.py;h=e4d5f6e9a42fe4726c5dff35e9488e13b61eea13;hb=4c0b3ff23b3d9fc526dfaa4803eb167d64c32181;hp=fe67e5cc799303efada094f510b537616a30bbd0;hpb=4815fe5c7be508e67ceec144968a81bdd6a923d4;p=plomtask diff --git a/plomtask/db.py b/plomtask/db.py index fe67e5c..e4d5f6e 100644 --- a/plomtask/db.py +++ b/plomtask/db.py @@ -4,7 +4,7 @@ from os.path import isfile from difflib import Differ from sqlite3 import connect as sql_connect, Cursor, Row from typing import Any, Self, TypeVar, Generic -from plomtask.exceptions import HandledException +from plomtask.exceptions import HandledException, NotFoundException PATH_DB_SCHEMA = 'scripts/init.sql' EXPECTED_DB_VERSION = 0 @@ -75,7 +75,7 @@ class DatabaseConnection: """Close DB connection.""" self.conn.close() - def rewrite_relations(self, table_name: str, key: str, target: int, + def rewrite_relations(self, table_name: str, key: str, target: int | str, rows: list[list[Any]]) -> None: """Rewrite relations in table_name to target, with rows values.""" self.delete_where(table_name, key, target) @@ -102,7 +102,8 @@ class DatabaseConnection: return [row[0] for row in self.exec(f'SELECT {column} FROM {table_name}')] - def delete_where(self, table_name: str, key: str, target: int) -> None: + def delete_where(self, table_name: str, key: str, + target: int | str) -> None: """Delete from table where key == target.""" self.exec(f'DELETE FROM {table_name} WHERE {key} = ?', (target,)) @@ -120,9 +121,34 @@ class BaseModel(Generic[BaseModelId]): """Template for most of the models we use/derive from the DB.""" table_name = '' to_save: list[str] = [] + to_save_versioned: list[str] = [] + to_save_relations: list[tuple[str, str, str]] = [] id_: None | BaseModelId cache_: dict[BaseModelId, Self] + def __init__(self, id_: BaseModelId | None) -> None: + if isinstance(id_, int) and id_ < 1: + msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}' + raise HandledException(msg) + self.id_ = id_ + + def __eq__(self, other: object) -> bool: + if not isinstance(other, self.__class__): + return False + to_hash_me = tuple([self.id_] + + [getattr(self, name) for name in self.to_save]) + to_hash_other = tuple([other.id_] + + [getattr(other, name) for name in other.to_save]) + return hash(to_hash_me) == hash(to_hash_other) + + def __lt__(self, other: Any) -> bool: + if not isinstance(other, self.__class__): + msg = 'cannot compare to object of different class' + raise HandledException(msg) + assert isinstance(self.id_, int) + assert isinstance(other.id_, int) + return self.id_ < other.id_ + @classmethod def get_cached(cls: type[BaseModelInstance], id_: BaseModelId) -> BaseModelInstance | None: @@ -173,25 +199,42 @@ class BaseModel(Generic[BaseModelId]): return obj @classmethod - def _by_id(cls, - db_conn: DatabaseConnection, - id_: BaseModelId) -> tuple[Self | None, bool]: - """Return instance found by ID, or None, and if from cache or not.""" - from_cache = False - obj = cls.get_cached(id_) + def by_id(cls, db_conn: DatabaseConnection, + id_: BaseModelId | None, + # pylint: disable=unused-argument + create: bool = False) -> Self: + """Retrieve by id_, on failure throw NotFoundException. + + First try to get from cls.cache_, only then check DB; if found, + put into cache. + + If create=True, make anew (but do not cache yet). + """ + obj = None + if id_ is not None: + obj = cls.get_cached(id_) + if not obj: + for row in db_conn.row_where(cls.table_name, 'id', id_): + obj = cls.from_table_row(db_conn, row) + obj.cache() + break if obj: - from_cache = True - else: - for row in db_conn.row_where(cls.table_name, 'id', id_): - obj = cls.from_table_row(db_conn, row) - obj.cache() - break - return obj, from_cache + return obj + if create: + obj = cls(id_) + return obj + raise NotFoundException(f'found no object of ID {id_}') @classmethod def all(cls: type[BaseModelInstance], db_conn: DatabaseConnection) -> list[BaseModelInstance]: - """Collect all objects of class.""" + """Collect all objects of class into list. + + Note that this primarily returns the contents of the cache, and only + _expands_ that by additional findings in the DB. This assumes the + cache is always instantly cleaned of any items that would be removed + from the DB. + """ items: dict[BaseModelId, BaseModelInstance] = {} for k, v in cls.get_cache().items(): assert isinstance(v, cls) @@ -199,27 +242,46 @@ class BaseModel(Generic[BaseModelId]): already_recorded = items.keys() for id_ in db_conn.column_all(cls.table_name, 'id'): if id_ not in already_recorded: - # pylint: disable=no-member - item = cls.by_id(db_conn, id_) # type: ignore[attr-defined] + item = cls.by_id(db_conn, id_) + assert item.id_ is not None items[item.id_] = item return list(items.values()) - def set_int_id(self, id_: int | None) -> None: - """Set id_ if >= 1 or None, else fail.""" - if (id_ is not None) and id_ < 1: - msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}' - raise HandledException(msg) - self.id_ = id_ # type: ignore[assignment] + def save(self, db_conn: DatabaseConnection) -> None: + """Write self to DB and cache and ensure .id_. + + Write both to DB, and to cache. To DB, write .id_ and attributes + listed in cls.to_save[_versioned|_relations]. - def save_core(self, db_conn: DatabaseConnection, - update_with_lastrowid: bool = True) -> None: - """Write bare-bones self (sans connected items), ensuring self.id_.""" + Ensure self.id_ by setting it to what the DB command returns as the + last saved row's ID (cursor.lastrowid), EXCEPT if self.id_ already + exists as a 'str', which implies we do our own ID creation (so far + only the case with the Day class, where it's to be a date string. + """ values = tuple([self.id_] + [getattr(self, key) for key in self.to_save]) q_marks = DatabaseConnection.q_marks_from_values(values) table_name = self.table_name cursor = db_conn.exec(f'REPLACE INTO {table_name} VALUES {q_marks}', values) - if update_with_lastrowid: + if not isinstance(self.id_, str): self.id_ = cursor.lastrowid # type: ignore[assignment] self.cache() + for attr_name in self.to_save_versioned: + getattr(self, attr_name).save(db_conn) + for table, column, attr_name in self.to_save_relations: + assert isinstance(self.id_, (int, str)) + db_conn.rewrite_relations(table, column, self.id_, + [[i.id_] for i + in getattr(self, attr_name)]) + + def remove(self, db_conn: DatabaseConnection) -> None: + """Remove from DB and cache, including dependencies.""" + if self.id_ is None or self.__class__.get_cached(self.id_) is None: + raise HandledException('cannot remove unsaved item') + for attr_name in self.to_save_versioned: + getattr(self, attr_name).remove(db_conn) + for table, column, attr_name in self.to_save_relations: + db_conn.delete_where(table, column, self.id_) + self.uncache() + db_conn.delete_where(self.table_name, 'id', self.id_)